JPH0119452Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a feeding horn having a corrugated waveguide and suitable for use in a multi-horn shaped beam antenna. By arranging the horn antenna, the physical size of the aperture of the horn antenna is small, and a broadband shaped beam antenna with good electrical performance that can radiate a sharp antenna beam is realized.

Conventionally, feeding horns for multi-beam shaped beam antennas with good electrical performance have been, for example, a cross-shaped aperture horn with a cross-shaped opening 1 as shown in Figure 1, or a circular horn as shown in Figure 2. A step horn in which a waveguide 2 and a circular opening 3 are connected by a step portion 4 has been widely used.

However, the cross-aperture horn has the disadvantage that cross-polarized components are emitted in diagonal directions of the aperture, and their magnitude gradually increases as the operating frequency increases. In step horns, step part 4
A phase adjustment unit 5 is required to generate the TM ₁₁ mode and match the phase with the TE ₁₁ mode propagated through the cylindrical waveguide 2 at the circular aperture 3 of the horn, which has the disadvantage of making it difficult to maintain broadband characteristics. It was hot.

Therefore, an object of the present invention is to provide a feeding horn that eliminates the above-mentioned drawbacks, has a small physical size, can obtain broadband characteristics, and is suitable for constructing a shaped beam antenna. It is in.

In order to achieve such an objective, the present invention includes a corrugated waveguide having a plurality of corrugated grooves, an input opening end connected to the output end of the corrugated waveguide, and a radiating section having an output opening end larger than the input opening end. The present invention is characterized in that a plurality of power supply horn units having a plurality of power supply horn units are arranged in parallel, and the aperture surfaces of the output opening ends of the respective radiating portions of the plurality of power supply horn units are arranged on substantially the same plane.

The present invention will be described in detail below with reference to the drawings.

An example of a power feeding horn unit as a structural unit in the power feeding horn of the present invention is shown in FIGS. 3 and 4. Here, 11 is an input flange, 12 is a corrugated waveguide, and 13 is a radiation section. The corrugated waveguide 12 has a plurality of corrugated grooves 12A,
A radiation section 13 consisting of a tapered waveguide with a circular cross section is provided at the output end 12B of the corrugated waveguide 12.
Connect the input end 13A of the.

Here, the corrugated waveguide 12 and the radiation section 1
3 is rotationally symmetrical with respect to the central axis XX'. The corrugated waveguide 12 has the same structure as a conventionally widely used corrugated horn, and the thickness of the teeth of the corrugated groove 12A is approximately λ/20, the spacing between the teeth is approximately λ/15, and the corrugated groove 12A has a tooth thickness of approximately λ/20. The depth of is approximately λ/4
shall be. Here, λ is the free space wavelength.

No corrugated groove is provided in the radiation part 13.
The inner diameter of the input end 13A of No. 3 is the corrugated waveguide 12.
The diameter is the same as the inner diameter of the output end 12B of the corrugated waveguide 12, so that it can be smoothly connected to the corrugated waveguide 12. The inner diameter D ₂ of the output end 13B of the radiation section 13 is
Make it larger than the inner diameter _D1 of the input end 13A. This inner diameter D ₂ determines the electrical size of the horn opening. The outer diameter _D3 of the output end 13B of the radiation section 13 is made the same as the outer diameter of the corrugated section output end 12B.
This outer diameter D ₃ defines the physical size of the horn. The length l of the radiating section 13 determines the taper angle θ ₂ in the radiating section 13, and is made to be approximately equal to or slightly larger than the taper θ ₁ of the corrugated waveguide 12. In addition,
When D ₃ and D ₂ are equal, the horn has the same electrical aperture size and physical aperture size. However, even in this case, it is necessary to design the wall surface of the radiation section 13 so that it always has a predetermined thickness, for example, about 0.5 mm.

The electric field distribution on the aperture surface of the radiation section 13 can be determined as follows.

Considering that the electric field distribution on the aperture surface at the output end 12B of the corrugated waveguide 12 can be approximated by combining the TE ₁₁ mode and the TM ₁₁ mode, the electric field in the θ direction of the E plane when there is no radiation section 13 is Eθ _E = C ₀ (1-α/1-(3.832/u) ² ) (J ₁ u/u
)e ^-jkR /R
…(1) is given. . Here, u is u=πD ₁ /λsinθ (2), and C ₀ is a constant. R is the distance from the center of the horn to the observation point. k is a constant;
=2π/λ. λ represents the free space wavelength.
Note that here it is assumed that R≫λ.

The electric field in the θ direction of the H plane is Eθ _H = C ₁ (J ₁ ′u/1−(u/1.841) ² )e ^-jkR /R…
(3) is given by

Since the E and H planes of the radiation pattern of the corrugated horn match very well, α, which matches the patterns of equations (1) and (3) very well, is found, and the radiation part 13
The radiation pattern in the case where there is no corrugated horn, that is, it corresponds only to a corrugated horn, can be calculated using the above α in equation (1).
When approximated by Eθ _E and Eθ _H in equation (3), the radiation part 1
3, the radiation pattern when there is this radiation part 13
_Let ^Δφ be ^the _{difference in} phase change between TE ₁₁ mode and TM ₁₁ mode in
u/u)e ^-jkR /R
…(4) Eθ _H =C ₁ (J ₁ ′u/1−(u/1.841) ² )e ^-jkR /R…
(5) is given by Here, u is u=πD ₂ /λsinθ (6).

The value of Δφ becomes smaller as l becomes smaller, and changes due to frequency can be almost ignored within a range where l is small.

Figure 5 shows the dimensions of the feeding horn unit in the feeding horn of the present invention, l = 21 mm, D ₁ = 52 mm, D ₂ =
The figure shows the radiation pattern of the main polarized wave when this horn antenna is excited with circularly polarized waves, assuming a diameter of 56 mm. In FIG. 5, the radiation pattern measured only with the corrugated waveguide 12 is also shown by a broken line for comparison. From FIG. 5, it can be seen that according to the present invention, the effect of the radiation part is manifested. Although not shown in the figure, the cross-polarized component at the point where the main polarized component is -10 dB is about -23 dB, which is about 3 dB better than a normal conical horn.

In the feeding horn unit of the feeding horn of the present invention, unlike a multi-mode horn such as a conventional step horn, the radiating part 13 is excited by a corrugated waveguide 12 with a very wide band, so the characteristics of the horn can be made into a wide band. At the same time, as the length l of the radiation part 13 becomes shorter, the radiation part 1
The influence of 3 is also reduced. Furthermore, the widening of the aperture at the output end 13B of the radiation section 13 makes it possible to make the radiation beam narrow and sharp.

If a conventional corrugated horn is simply used as the feeding horn of a multi-horn type shaped beam antenna, the physical aperture size becomes large due to the corrugated grooves, and therefore the beam spacing of the multi-beam becomes too large. However, in the present invention, multiple feeding horn units are used and their apertures are arranged on the same plane to form a multi-beam shaped beam antenna. Since it is possible to make the size of the physical aperture of the horn close to the size of the electrical aperture while taking advantage of its broadband characteristics, the beam spacing of multiple beams can be narrowed.

As an example of a multi-beam shaped beam antenna using the feeding horn of the present invention, a broadcasting antenna mounted on an artificial satellite is shown in FIG. Here, 21
and 22 are power feeding horn units in the power feeding horn of the present invention, and the opening surfaces of these horn units 21 and 22 are arranged on the same plane. Reference numeral 23 denotes an offset parabolic reflector with an aperture angle of, for example, 64 degrees, and the center of the aperture of one feed horn 21 is placed at the focal point F, and the center of the aperture of the other feed horn 22 is 2.2 degrees from the focal point F. Place it at a point P shifted by °. In other words, one point 0 of parabola 23
Assume that the angle between points F and P is 2.2°.
In order to arrange it in this way, it is necessary to change the physical aperture diameter (Fig. 4 D
3) is not small, the adjacent horns will become an obstacle and cannot be placed. Furthermore, in order to efficiently irradiate the parabola 23, the radiation pattern of the horn cannot be made too broad. Therefore, it is understood that it is necessary to make the physical aperture diameter of the horn smaller than the beam width of the radiation pattern. By supplying signals of different frequency bands to these power supply horn units 21 and 22 from individual power supply devices 24 and 25, the beams from the parabola 23 are directed to separate service areas 26 and 27 with narrow beam spacing. It can emit radio waves.

In the above example, the present invention has been explained for the case where the shape of the aperture is circular, but the aperture can also have any desired shape. The feeding horn of the present invention can be configured with the radiating portion of the radiating portion, and in this case, the same analysis method as in the case of the circular aperture can be used.

As is clear from the above, according to the present invention, by using the feeding horn as the primary radiator of a multi-beam shaped beam antenna, the distance between adjacent horns can be reduced, and moreover, it is possible to excite with circularly polarized waves. It is possible to maintain good cross-polarization characteristics over a wide frequency range. Therefore, as shown in Figure 6, the shape of the service area is determined and the beam spacing between adjacent antenna beams must be narrowed, such as the shaped beam antenna mounted on a Japanese broadcasting satellite. By using the feeding horn of the present invention as the primary radiator of a shaped beam antenna, a shaped beam antenna with a good degree of beam shaping can be realized.

[Brief explanation of drawings]

1 and 2 are perspective views showing two examples of conventional power feeding horns, and FIGS. 3 and 4 are perspective views and sectional views, respectively, showing an example of a power feeding horn unit in the power feeding horn of the present invention. FIG. 5 is a diagram showing an actual measurement example of the radiation pattern of the main polarized wave, and FIG. 6 is an explanatory diagram of a shaped beam antenna using the feeding horn of the present invention. DESCRIPTION OF SYMBOLS 1... Cross aperture, 2... Cylindrical waveguide, 3... Circular aperture, 4... Step part, 5... Phase adjustment part,
11... Input flange, 12... Corrugated waveguide, 12A... Corrugated groove, 12B... Output end, 13... Radiation section, 13A... Input end, 13B
...Output end.

Claims (1)

[Claims for Utility Model Registration] 1. A corrugated waveguide having a plurality of corrugated grooves, an input opening end connected to the output end of the corrugated waveguide, and a radiating section having an output opening end larger than the input opening end. A power feeding horn characterized in that a plurality of power feeding horn units having a plurality of power feeding horn units are arranged in parallel, and opening surfaces of output opening ends of respective radiating parts of the plurality of power feeding horn units are arranged on substantially the same plane. 2 Utility Model Registration Scope of Claims In the power feeding horn according to claim 1, the shape of the outer wall and inner wall of the input opening end is the same as the shape of the output end of the corrugated waveguide, and the inner wall surface of the radiating part is A power supply horn characterized by a tapered surface. 3 Utility Model Registration The power feeding horn according to claim 2, wherein each cross section of the corrugated waveguide and the radiation portion is circular. 4 Utility Model Registration The power feeding horn according to claim 2, characterized in that each cross section of the corrugated waveguide and the radiation portion is elliptical.